Study of Effective Graded Oxide Capacitance and Length Variation on Analog, RF and Power Performances of Dual Gate Underlap MOS-HEMT

Abstract

Comparative analysis of a Symmetric Heterojunction Underlap Double Gate (U-DG) GaN/AlGaN Metal Oxide Semiconductor High Electron Mobility Transistor (MOS-HEMT) on varying the effective capacitance by using different oxide materials on source and drain sides, and determination of optimum length of oxides for the superior device performance has been presented in this work. This paper shows a detailed performance analysis of the Analog Figure of Merits (FoMs) like variation of Drain Current (IDS), Transconductance (gm), Output Resistance (R0), Intrinsic Gain (gmR0), RF FoMs like cut-off frequency (fT), maximum frequency of oscillation (fMAX), gate to source resistance (RGS), gate to drain resistance (RGD), gate to drain capacitance(CGD), gate to source capacitance (CGS) and total gate capacitance (CGG) using Non-Quasi-Static (NQS) approach. Power analysis includes Output power (Pout), Gain in dBm and power output efficiency (POE) have been studied. Studies reveal that the device with higher dielectric material towards source side shows superior performance. On subsequently changing the proportion of two oxides in a layer by varying length, it is observed that as the proportion of oxide increases the device demonstrates more desirable Analog and RF characteristics while best power performance is obtained from device with equal lengths of HfO2 and SiO2.